DC Pipe and Parts

[poolhound]

Connecting 4" hose to 4" pipe

Yesterday I started laying the 4" ductwork (PVC) for my DC setup. I see I will need some form of adapter/transition to go from the PVC pipe to standard 4" flex to attach to the various tools.

I could not find anything appropriate in PVC at the borg yesterday although I think using some 4" HVAC metal might work. What have others done to make this transition?

[JoeyGee]

Jon, not sure if this helps, but Jay Bates has a video on making blast gates in which he talks about making the transition from PVC to the hose using blast gates. The key seems to be using PVC couplers.

http://jayscustomcreations.com/2014/08/how-to-make-4-pvc-blast-gates/

[LCHIEN]

... Maybe toss a chunk of wood in the bottom of you're worried about it getting sucked up.

I think I saw in a magazine shop tip to use a coil of rebar wire mesh in the can to keep the bag in place and pushed against the sides of the can. When it's filled, you lift the wire mesh out.

...

if your can is perfectly sealed then there is no pressure behind the liner bag.

But if it has a hole then you have atmospheric pressure behind the bag and a near vacuum on the top.

Assuming a 20" dia x 20" tall can the area of the sides is roughly 63x20 =1260 sq in and the bottom is about 3.1 x 10 x 10= 310 sq in for a total of 1570 sq inches.

Now assume you have a so-so vacuum of 5 inches of water which is about .18PSI then the force lifting the bag will be 283 pounds.

I don't think a block of wood will hold it down and if the block of wood hits the impeller it will be worse than the bag hitting the impeller.

If the hole is a small leak it will happen more slowly but eventually reach 283 pounds.You are not going to be able to hold that bag down if there's a leak or a hole in the can.

[Bill in Buena Park]

Jon,
I made some adapters with a connector, a hose clamp, duct tape, and a piece of the piping. I had to put slits in the piping to fit over the connector, which is why I needed the duct tape (as shown below). These have worked pretty well for the past few years, I occasionally have to tighten the hose clamps and I've only had to refresh the duct tape once.

[JimD]

I found I could force 4 inch flex inside the coupling end of the 4 inch thin walled plastic pipe. It was a tight friction fit and I added some duct tape to it to seal. It worked well on the jointer but I kicked it too often on the table saw and it would come apart and be a pain. But if you can arrange things where it isn't getting stepped on or otherwise messed with, this will work.

[poolhound]

I found I could force 4 inch flex inside the coupling end of the 4 inch thin walled plastic pipe. It was a tight friction fit and I added some duct tape to it to seal. It worked well on the jointer but I kicked it too often on the table saw and it would come apart and be a pain. But if you can arrange things where it isn't getting stepped on or otherwise messed with, this will work.

Yup I have tried that in the past and had the same experience. Rockler and woodcraft seem to have what looks like the same fittings that claim to make this transition. as I am lucky to have a rockler 2 miles from my house I will check out what they have. At least its not too far to go if I have to take it back :-)

[capncarl]

Poolhound, the lid shoud be more than adequate without additional bracing.
In a previous job I was involved in design and installing many dust and vacuum systems. I've kept my mouth shut and opinions about dust collectors to myself as to avoid stepping on someone's feelings. (We transported millions of pounds of peanuts via airveyor systems. The receivers were small cyclones. Our vacuum systems for waste handled particle sizes smaller than .5 micron using large cyclones and bag houses larger than semi trailers.) When you are dealing with the size vacuum system that is sold for home shop use the most important thing about the cyclone or Thein separator is its diameter. Bigger dia. is better. Particles (objects larger than dust) must have an area to drop out of the airflow. This could be an airtight box rather than a drum. A cyclone or Thein must allow the air velocity to reduce to whatever speed that particle needs to drop out. It doesn't matter much what size cyclone, Thein or box you use airborne dust will not drop out. (Airborne dust is any dust you can see in sunlight in the shop that goes everywhere and coats everything) The only thing that gets this dust out is a filter bag or pleated filter. The airborne dust is really the bad character for woodworkers because you breathe in this dust, not the wood chips and saw dust that we try so much to capture. We must keep the systems efficiency up and capture the dust out of the return air.